fix grabFromDatabase description in docs

docs/modules/Db.md

@@ -271,18 +271,28 @@ $mails = $I->grabColumnFromDatabase('users', 'email', array('name' => 'RebOOter'
 
 ### grabFromDatabase
 
-Fetches all values from the column in database.
+Fetches a single column value from a database.
 Provide table name, desired column and criteria.
 
 ``` php
 <?php
-$mails = $I->grabFromDatabase('users', 'email', array('name' => 'RebOOter'));
+$mail = $I->grabFromDatabase('users', 'email', array('name' => 'Davert'));
+```
+Comparison expressions can be used as well:
+
+``` php
+<?php
+$post = $I->grabFromDatabase('posts', ['num_comments >=' => 100]);
+$user = $I->grabFromDatabase('users', ['email like' => 'miles%']);
 ```
 
+Supported operators: `<`, `>`, `>=`, `<=`, `!=`, `like`.
+
  * `param string` $table
  * `param string` $column
  * `param array`  $criteria
-
+
+ * `return` mixed Returns a single column value or false
 
 
 ### grabNumRecords

src/Codeception/Module/Db.php

@@ -883,19 +883,28 @@ public function grabColumnFromDatabase($table, $column, array $criteria = [])
     }
 
     /**
-     * Fetches all values from the column in database.
+     * Fetches a single column value from a database.
      * Provide table name, desired column and criteria.
      *
      * ``` php
      * <?php
-     * $mails = $I->grabFromDatabase('users', 'email', array('name' => 'RebOOter'));
+     * $mail = $I->grabFromDatabase('users', 'email', array('name' => 'Davert'));
+     * ```
+     * Comparison expressions can be used as well:
+     *
+     * ```php
+     * <?php
+     * $post = $I->grabFromDatabase('posts', ['num_comments >=' => 100]);
+     * $user = $I->grabFromDatabase('users', ['email like' => 'miles%']);
      * ```
      *
+     * Supported operators: `<`, `>`, `>=`, `<=`, `!=`, `like`.
+     *
      * @param string $table
      * @param string $column
-     * @param array  $criteria
+     * @param array $criteria
      *
-     * @return mixed
+     * @return mixed Returns a single column value or false
      */
     public function grabFromDatabase($table, $column, $criteria = [])
     {